Steel sheet for containers and method for producing steel sheet for containers

Abstract

A steel sheet for a container according to the present invention includes: a base steel sheet; a metal chromium layer; and a chromium-containing layer, in which the metal chromium layer is located on at least one surface of the base steel sheet, the chromium-containing layer is located on the metal chromium layer and contains a granular trivalent chromium compound, or contains a granular trivalent chromium compound and granular metal chromium, the metal chromium layer and the chromium-containing layer are separately disposed in two layers on the base steel sheet, in the chromium-containing layer, an average particle size of the trivalent chromium compound and the metal chromium is 10 nm or more and 100 nm or less, and an adhesion amount of the chromium-containing layer is 1.0 mg/m2 or more and 100 mg/m2 or less in terms of a Cr content.

The invention claimed is: 
     
       1. A steel sheet, comprising:
 a base steel sheet; 
 a metal chromium layer consisting of granular metal chromium particles with an average particle size of 10 nm or more and 100 nm or less; and 
 a chromium-containing layer, 
 wherein the metal chromium layer is located on at least one surface of the base steel sheet, 
 the chromium-containing layer is located on the metal chromium layer and contains a granular trivalent chromium compound, or contains a granular trivalent chromium compound and a granular metal chromium, 
 the metal chromium layer and the chromium-containing layer are separately disposed in two layers on the base steel sheet, 
 in the chromium-containing layer, an average particle size of the trivalent chromium compound and the metal chromium is 10 nm or more and 100 nm or less, and 
 an adhesion amount of the chromium-containing layer is 1.0 mg/m2 or more and 100 mg/m2 or less in terms of a Cr content, 
 wherein the metal chromium layer and the chromium-containing layer contain a total amount of 6 mg/m 2  or more and 80 mg/m 2  or less of a sulfate compound in terms of a S content. 
 
     
     
       2. The steel sheet according to  claim 1 ,
 wherein an adhesion amount of the metal chromium layer is 1.0 mg/m2 or more and 350 mg/m2 or less in terms of the Cr content. 
 
     
     
       3. The steel sheet according to  claim 1 ,
 wherein the chromium-containing layer contains a sulfate compound in an amount of 0.10 mg/m2 or more and 40 mg/m2 or less in terms of a S content. 
 
     
     
       4. A method for producing the steel sheet of  claim 1 , the method comprising:
 a chemical conversion step of treating a base steel sheet with a plurality of chemical conversion baths and forming a metal chromium layer and a chromium-containing layer containing a granular trivalent chromium compound or containing a granular trivalent chromium compound and a granular metal chromium on the metal chromium layer, the metal chromium layer and the chromium-containing layer being separated into two layers on at least one surface of the base steel sheet, 
 wherein the plurality of chemical conversion baths contain 0.10 to 250 g/L of trivalent chromium ions, 27 to 250 g/L of sulfate ions, 1.0 to 250 g/L of formate ions, and 1.0 to 150 g/L of borate ions, 
 a pH of the plurality of chemical conversion baths is 3.0 or more, and 
 an electroless time of 0.1 seconds or longer and 20 seconds or shorter is provided when the base steel sheet is moved between the plurality of chemical conversion baths thereby producing said steel sheet for a container. 
 
     
     
       5. The method for producing a steel sheet according to  claim 4 ,
 wherein, in the chemical conversion step, a temperature of the plurality of chemical conversion baths is 5° C. or higher and lower than 90° C. 
 
     
     
       6. The method for producing a steel sheet according to  claim 4 ,
 wherein, in the plurality of chemical conversion baths, the base steel sheet is subjected to an electrolytic treatment at a current density of 0.5 A/dm2 or more and 50 A/dm2 or less for 0.05 seconds or longer and 10 seconds or shorter. 
 
     
     
       7. The method for producing a steel sheet according to  claim 4 ,
 wherein the plurality of chemical conversion baths further contain 1.0 to 100 g/L of chloride ions and 1.0 to 100 g/L of potassium ions. 
 
     
     
       8. A container, comprising:
 a steel sheet, wherein the steel sheet comprises: 
 a base steel sheet; 
 a metal chromium layer consisting of granular metal chromium particles with an average particle size of 10 nm or more and 100 nm or less; and 
 a chromium-containing layer, 
 wherein the metal chromium layer is located on at least one surface of the base steel sheet, 
 the chromium-containing layer is located on the metal chromium layer and contains a granular trivalent chromium compound, or contains a granular trivalent chromium compound and a granular metal chromium, 
 the metal chromium layer and the chromium-containing layer are separately disposed in two layers on the base steel sheet, 
 in the chromium-containing layer, an average particle size of the trivalent chromium compound and the metal chromium is 10 nm or more and 100 nm or less, and 
 an adhesion amount of the chromium-containing layer is 1.0 mg/m 2  or more and 100 mg/m 2  or less in terms of a Cr content, 
 wherein the metal chromium layer and the chromium-containing layer contain a total amount of 6 mg/m 2  or more and 80 mg/m 2  or less of a sulfate compound in terms of a S content.